The invention relates to the use of polyamide moulding compounds, whose alloys or blends, which have at least one homopolyamide, for optical or electro-optical purposes.
Transparent plastics are used in an increasing number of applications as a replacement for mineral glass etc., but also as a replacement for further materials. The reasons for this are the considerable economy in weight, simplicity of cleaning, simple re-use, much improved recycling, more versatile, more rapid and more risk-free applicability, the many possibilities of providing special properties, the fashionable effect, economic disposal and increasingly competitive prices.
In addition to the transparent plastics such as PMMA, PS, ABS, PVC, cellulose butyrate, cellulose acetate, CR 39 which in part have been known for some time, there have become known further materials such as PC, SAN, SB, CAP, PET, PBT, PSU, PVF, PU, APEC, COC and amorphous polyolefines. In addition to these, transparent polyamides have also become established and are to be encountered as operational parts in the automobile and electrical industries, in precision technology, medical technology and in the fashion industry.
In addition to PC, PMMA, among others, transparent polyamides are favoured materials for spectacle frames and spectacle lenses; they have however not been used in the actual optical field as lenses, magnifying glasses, sun-glasses, etc. due to the lack of transparency, purity, toughness, resistance to solvents, scratch resistance (scratch hardness) and dimensional stability. A disadvantage in these previously known transparent polyamides is above all that they do not simultaneously have a low density, a high refractive index and a high Abbe coefficient. These parameters however are extremely important particularly for optical applications of polyamides, as for example lenses should have not only a high refractive index and a high Abbe coefficient, but simultaneously also a relatively low density. only in this way is it possible to manufacture functional lenses, which also have the corresponding softness. In addition to these requirements, however, it is necessary for most optical and electro-optical applications that the materials in question here should be heat-resistant, solvent-resistant and scratch-resistant. In these applications there is also a requirement for the materials to have a high degree of alternate-bending fatigue strength and a high degree of toughness. Proceeding from this point it is the object of the present invention to propose polyamides which can be used for optical applications, in which on the one hand there is a high refractive index and a high Abbe coefficient and simultaneously a relatively low density. These polyamides are in addition intended to have a high degree of alternate-bending fatigue strength, resistance to chemicals and resistance to heat deformation.